Open AccessEmpirical calibration of the near‐infrared Ca ii triplet – III. Fitting functions
Author(s) -
Cenarro A.J.,
Gorgas J.,
Cardiel N.,
Vazdekis A.,
Peletier R.F.
Publication year - 2002
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2002.05029.x
Subject(s) - physics , surface gravity , metallicity , stars , line (geometry) , calibration , stellar population , effective temperature , surface (topology) , field (mathematics) , population , astrophysics , infrared , optics , quantum mechanics , geometry , mathematics , star formation , demography , sociology , pure mathematics
Using a near‐infrared stellar library of 706 stars with a wide coverage of atmospheric parameters, we study the behaviour of the Ca ii triplet strength in terms of effective temperature, surface gravity and metallicity. Empirical fitting functions for recently defined line‐strength indices, namely CaT*, CaT and PaT, are provided. These functions can be easily implemented into stellar population models to provide accurate predictions for integrated Ca ii strengths. We also present a thorough study of the various error sources and their relation to the residuals of the derived fitting functions. Finally, the derived functional forms and the behaviour of the predicted Ca ii are compared with those of previous works in the field.